JPH10269884A - Back-light control device for key operating part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To light a back-light only when brightness is insufficient and too dark for key operation and effectively use a secondary battery by judging whether or not to light the back-light based on the signal of a photo-sensor detecting the brightness of the ambient light. SOLUTION: When a numeral or a character is inputted from a key operating part 11, a dial button depression signal (a) is inputted to a control circuit 16, and the control circuit 16 turns on a transistor 15. When the transistor 15 is turned on, the voltage corresponding to the current flowing in a photo-sensor 13 appears at the end section of a resistor 14, and it is inputted to the control circuit 16 as the brightness level signal (b). The control circuit 16 judges whether the brightness level signal (b) is larger or smaller than a prescribed value, feeds the power from a secondary battery 17 to a back-light 12 to control the lighting of the back-light 12 when the signal (b) is smaller, and keeps the back- light 12 off without controlling its lighting when the signal (b) is larger.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight control device for illuminating a key operation unit from below in a portable information terminal device or a portable radio telephone device equipped with a secondary battery.

[0002]

2. Description of the Related Art Conventionally, the backlight of a key operation unit in a portable radio telephone device or the like is always lit when a dial button is pressed, even in a place bright enough to operate regardless of day or night. Is configured.
FIG. 4 is a block diagram of a conventional key operation unit backlight control device. In FIG. 4, reference numeral 1 denotes a key operation unit for inputting numbers and characters, etc., 2 denotes a backlight for illuminating the key operation unit 1 from below, and a denotes a dial generated when any dial button of the key operation unit 1 is pressed. A button press signal 3 is a control circuit that detects the dial button press signal a and controls the turning on and off of the backlight 2. Reference numeral 4 denotes a secondary battery that supplies power to the backlight 2.

[0003] The operation of the key operation unit control device configured as described above will be described below. When a number, a character, or the like is input from the key operation unit 1, a dial button press signal a is input to the control circuit 3. When detecting the dial button press signal a, the control circuit 3 performs control to turn on the backlight 2 illuminating the key operation unit 1. This gives 2
Power is supplied from the next battery 4, and the battery capacity is consumed.

[0004]

However, in the above-mentioned conventional key operation unit backlight control device, even when the illuminance is sufficient such as in the daytime and the numbers and characters of the key operation unit 1 can be sufficiently recognized, the control circuit 3 controls the dial. When the button press signal a is detected, the backlight 2 is turned on.
There was a problem that the battery capacity of the secondary battery was wasted.

The present invention solves such a conventional problem. The backlight is not turned on when the key operation is sufficiently bright, and only when the brightness is insufficient and the key operation is dark. It is an object of the present invention to provide a key operation unit backlight control device capable of effectively using the power of a secondary battery by turning on a backlight.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention detects ambient brightness with an optical sensor and determines whether or not to turn on a backlight based on the signal, By not turning on the backlight when it is bright enough to operate the keys, and turning on the backlight only when the brightness is insufficient and it is dark to operate the keys,
The power of the secondary battery is used effectively.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention comprises a backlight for illuminating a key operation section from below, an optical sensor for detecting the brightness around the housing of the apparatus body, and And a means for controlling the turning on and off of the backlight based on the signal of the key operation unit, and controls the backlight only when the surrounding brightness is insufficient and the key operation is dark. Lighting has the effect that the power of the secondary battery can be used effectively.

According to a second aspect of the present invention, there is provided a key operation device according to the first aspect, wherein the sensor is disposed inside the housing, and external light is detected through a lighting hole provided in the housing. The backlight control device has a function of simplifying wiring to the optical sensor.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a circuit configuration of a key operation unit backlight control device according to the present embodiment. In FIG. 1, reference numeral 11 denotes a key operation unit for inputting numbers, characters, and the like, reference numeral 12 denotes a backlight for illuminating the key operation unit 11 from below, reference numeral 13 denotes an optical sensor for detecting the brightness around the housing of the apparatus body, and reference numeral 14 denotes A resistor for converting a current flowing when the optical sensor 13 receives light into a voltage, a switching transistor 15, a collector connected to the resistor 14, a base connected to the control circuit 16, and an emitter connected to the ground, respectively. I have. Reference numeral 16 denotes a control circuit for controlling turning on and off of the backlight 12 according to a signal from the optical sensor 13, and reference numeral 17 denotes a secondary battery for supplying power to the backlight 12.

FIG. 2 shows the appearance of a portable radio telephone device to which the key operation unit backlight control device of the present invention is applied. A plurality of operation buttons 22 are provided on the front of a housing 21. A backlight 23 composed of a light emitting diode is arranged below the light emitting diode 22, and an optical sensor 25 is arranged below a lighting hole 24 provided in the housing 21.

FIGS. 3A and 3B show another example of a portable radio telephone apparatus to which the key operation unit backlight control device of the present invention is applied, wherein FIG. 3A shows an external front view, and FIG. 3B shows an internal front view. Is shown. A plurality of operation buttons 32 are provided on the front surface of the housing 31, a backlight 34 made of a light emitting diode is attached to a substrate 33 below the operation buttons 32, and a light receiving hole 35 provided in the housing 31 is provided. The optical sensor 36 is attached to the position of the substrate 33 on the side.

Next, the operation of the key operation unit backlight control device configured as described above will be described with reference to FIG. When a number or character is input from the key operation unit 11,
A dial button press signal a is input to the control circuit 16. When the control circuit 16 detects the dial button press signal a, the control circuit 16 controls the transistor 1 to detect the ambient brightness.
5 is turned on to turn on the transistor 15. When the transistor 15 is turned on, a voltage corresponding to the current flowing through the optical sensor 13 appears at the end of the resistor 14, and this is input to the control circuit 16 as a brightness level signal b. The control circuit 16 determines whether or not the brightness level signal b is larger or smaller than a predetermined value. If the brightness level signal b is smaller than the predetermined value, the control circuit 16 performs control for turning on the backlight 12, and Supply power from 17. When it is determined that the size is large, the backlight 12 is kept turned off without performing control.

As described above, according to the present embodiment, the light sensor 13, the resistor 14, and the transistor 15 constitute a brightness detection circuit, and the brightness detection circuit detects the brightness around the housing. Only when the brightness is below a certain value,
Since the backlight 12 is turned on, useless consumption of the secondary battery 17 can be suppressed.

[0014]

As described above, according to the present invention, the backlight for illuminating the key operation unit from below, the optical sensor for detecting the brightness around the housing of the apparatus main body, and the signal from the optical sensor are also provided. And a means for controlling the turning on and off of the backlight, so that the backlight can be turned on and off efficiently according to the brightness around the housing, and unnecessary power consumption of the secondary battery can be suppressed. Can be used effectively.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of a key operation unit backlight control device according to an embodiment of the present invention.

FIG. 2 is a perspective view showing the appearance of a portable wireless telephone device to which the present invention is applied.

3A is a front view showing the appearance of another portable wireless telephone device to which the present invention is applied; FIG. 3B is a front view showing the inside of the device;

FIG. 4 is a block diagram showing a circuit configuration of a conventional key operation unit backlight control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Key operation part 12 Backlight 13 Optical sensor 14 Resistor 15 Transistor 16 Control circuit 17 Secondary power supply 21, 31 Housing 22, 32 Operation buttons 23, 34 Backlight 24, 35 Lighting window 25, 36 Optical sensor 33 Substrate a Dial button press signal b Brightness level signal

Claims (2)

[Claims] 1. A backlight for illuminating a key operation unit from below, an optical sensor for detecting brightness around a housing of an apparatus body, and turning on and off of the backlight based on a signal from the optical sensor. And a key operation unit backlight control device. 2. The key operation unit backlight control device according to claim 1, wherein an optical sensor is disposed inside the housing, and detects external light through a lighting hole provided in the housing.